8 replies to this topic

[Doom]

I've had this made for about 3 weeks but lately I've been just tinkering with it. I originally planned it to be a semi-auto type gun but I am just not figuring out how to do that from where I am. It was a test, using only leftover parts because I was hoping to work out the bugs this way (and I'm broke). The design, left as it is now, still will have a relatively high ROF, it does everything I wanted it to except reload the ammo. For now you can do that manually, and that's all you have to do because it has a large CPS tube hooked up to it.

http://www.sscentral...to/DSCN0102.JPG

You can see the gun in all of it's early glory (the pic's 2 1/2 weeks old). Since then I've added more rubber bands, cut that piece of PVC (you know, the one that is too long), added something to stop the barrel from extending and a few other minor things but it still looks something like that.

The basic theory I had was that I could make it have a retractable barrel that would grab the clip and lock it into place while opening the valve. How the clip worked or advanced I was hoping I'd figure out on the way, but I haven't yet.

The actual valve configuration is normally close, but when you push the upper handle forward (the thing on the top) or pull the lower handle back (about where those two screws are) and it will lock the sch. 80 thing in place and open the valve. You'd want to let go or retract it quickly then because it has no system to ration the air going through. The ball valve actually opens a few mms from when it actually makes contact with the clip which is pretty good, it took me a while and lots of measurement to get that.

http://www.sscentral...to/DSCN0105.JPG

There's the valve in it's open position. You can see that it pulled the barrel back, but you can't see it locked into the tee (unless you have some weird powers I don't). I've tested the system and fired off 6 shots in succession from about 40 or 50 pumps with that small AT 2K pump. The ratio of pumps to shots should be better when I get a better pump, that is what you get from leftover parts. Range on those shot's wasn't too good, around 60 feet level I am guessing. I can improve on that by either improving the CPS tube or using an air backpack and regulator.

I'm hoping to complete it soon, either by just finalizing it as it is or if any of you guys have any ideas on how I could make it semi-auto. Either way it gives me a good gun.

[ShortShit]

quite interresting! Keep us posted.

[Cadmond]

Yay for aluminum and ball valves!
Its only on one side though, so are there any twisting problems?

[Doom]

None, the 1 1/4" PVC was cut so it would prevent that, and the alluminum stuff without the 1 1/4" PVC actually will do it without twisting anyway (you just have to put one screw on tight). And twisting would only be a problem if I had a clip in it, but I likely would have found a way to fix that if I did. The 1 1/4" PVC also fits 1" PVC in nicely, that and 3/4" couplers (I cut all my couplers up before realizing they were the same size as 1" PVC). That's what made the thing lock into it, without it it's just a mess.

http://www.sscentral...to/DSCN0143.JPG
http://www.sscentral...to/DSCN0144.JPG

Two pics I took today, sorry to all because I'm not in the habit of resizing my pics. The second one is blurry, you get the basic idea though.

What is on top was going to be something that the clip would attach onto or stop at, but now it has evolved into some sight. Not very useful for that, but makes a good handle.

I also added a bunch of 1" PVC at the end of the barrel to keep it straight. When the first pics were taken only about half the time it would lock into it, the other half it would slam into the side. Now it locks in about 95% of the time.

I've thinking about adding some foam to the lower pull back type handle thing so it would be easier to hold. Any one have any ideas on how to modify the current design into a semi-auto one? That was my real reason in posting this, I was hoping at least someone could help. Also, does anyone have any other ideas that could help?

[Langley]

What sort of tubeing did you use for the tank? Did you take it out of another gun, or is it something you could buy from a store.

[Vassili]

Genious.

[Doom]

What sort of tubeing did you use for the tank? Did you take it out of another gun, or is it something you could buy from a store.

You can buy it from McMaster. It is called Latex Rubber Tubing. That's an old tube actually, it's thinned quite a lot. A new one, and a second one to make it thicker, should be bought. This however was made completely out of leftover parts, so I just took what I had. I think I stole that ball valve from a toilet now that I think of it...

I don't have another picture, but I've relocated the CPS tube to a backpack so I could use a butterfly valve as a cheap and semi-effective air regulation system. With the valve open it emptied the CPS tube (even with 150 or more pumps) in a matter of seconds. I think this should help.

The pump now has finally broken, it just gets too much use in this configuration and now leaks straight through it. I'm going to buy a new one on Friday. After shooting this thing off a number of times too I think it's needing some lubrication to let the barrel slide out better. I'll take some time off and do that after I get the pump.

No ideas on how I could make this semi-auto? I think I'll just leave it as it is at this point.

[okto]

whoa...it's fracking huge. why the gigantimous vertical pipe?

[Doom]

That was something I was hoping to use rubber bands with to attach a clip (since I don't have any real good springs). It never got use and I just kept it on. I think I said that too. It is fairly large actually, but retacts to about 6 inches shorter if you count that. It seriously is comparable to my homemade water guns in size (especially with that air backpack). I used to operating a gun that large so I don't think it would affect me very much. Anyway, I could easily cut that sch. 80 barrel shorter, I was planning on replacing it with brass.

Unless the size is completely ridiculous I don't think it's going to be a problem. I just need to find a way to put my stinking butterfly valve in the actual gun and make a case for the CPS tube and then it should be more manageable, the backpack is annoying as hell.